JPH021355B2 - - Google Patents
Info
- Publication number
- JPH021355B2 JPH021355B2 JP57196803A JP19680382A JPH021355B2 JP H021355 B2 JPH021355 B2 JP H021355B2 JP 57196803 A JP57196803 A JP 57196803A JP 19680382 A JP19680382 A JP 19680382A JP H021355 B2 JPH021355 B2 JP H021355B2
- Authority
- JP
- Japan
- Prior art keywords
- bromine
- zinc
- positive electrode
- electrolyte
- efficiency
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Lifetime
Links
- GDTBXPJZTBHREO-UHFFFAOYSA-N bromine Substances BrBr GDTBXPJZTBHREO-UHFFFAOYSA-N 0.000 claims description 55
- 229910052794 bromium Inorganic materials 0.000 claims description 54
- WKBOTKDWSSQWDR-UHFFFAOYSA-N Bromine atom Chemical compound [Br] WKBOTKDWSSQWDR-UHFFFAOYSA-N 0.000 claims description 52
- ZRXYMHTYEQQBLN-UHFFFAOYSA-N [Br].[Zn] Chemical compound [Br].[Zn] ZRXYMHTYEQQBLN-UHFFFAOYSA-N 0.000 claims description 26
- 239000003792 electrolyte Substances 0.000 claims description 26
- 239000011701 zinc Substances 0.000 claims description 22
- HCHKCACWOHOZIP-UHFFFAOYSA-N Zinc Chemical compound [Zn] HCHKCACWOHOZIP-UHFFFAOYSA-N 0.000 claims description 17
- 229910052725 zinc Inorganic materials 0.000 claims description 17
- 239000007774 positive electrode material Substances 0.000 claims description 5
- 208000028659 discharge Diseases 0.000 description 22
- 239000007788 liquid Substances 0.000 description 10
- 238000007599 discharging Methods 0.000 description 7
- 238000006243 chemical reaction Methods 0.000 description 5
- 230000000694 effects Effects 0.000 description 5
- 239000011149 active material Substances 0.000 description 4
- 238000009792 diffusion process Methods 0.000 description 4
- 238000000034 method Methods 0.000 description 4
- 230000005611 electricity Effects 0.000 description 3
- 239000012528 membrane Substances 0.000 description 3
- 239000000243 solution Substances 0.000 description 3
- 230000007423 decrease Effects 0.000 description 2
- 229910052751 metal Inorganic materials 0.000 description 2
- 239000002184 metal Substances 0.000 description 2
- BASFCYQUMIYNBI-UHFFFAOYSA-N platinum Chemical compound [Pt] BASFCYQUMIYNBI-UHFFFAOYSA-N 0.000 description 2
- JBQYATWDVHIOAR-UHFFFAOYSA-N tellanylidenegermanium Chemical compound [Te]=[Ge] JBQYATWDVHIOAR-UHFFFAOYSA-N 0.000 description 2
- VNDYJBBGRKZCSX-UHFFFAOYSA-L zinc bromide Chemical compound Br[Zn]Br VNDYJBBGRKZCSX-UHFFFAOYSA-L 0.000 description 2
- CPELXLSAUQHCOX-UHFFFAOYSA-M Bromide Chemical compound [Br-] CPELXLSAUQHCOX-UHFFFAOYSA-M 0.000 description 1
- -1 bromine ions Chemical class 0.000 description 1
- 238000005341 cation exchange Methods 0.000 description 1
- 239000000470 constituent Substances 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 239000008151 electrolyte solution Substances 0.000 description 1
- 238000002474 experimental method Methods 0.000 description 1
- 239000012530 fluid Substances 0.000 description 1
- 239000003014 ion exchange membrane Substances 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 239000012229 microporous material Substances 0.000 description 1
- 239000012982 microporous membrane Substances 0.000 description 1
- 239000000203 mixture Substances 0.000 description 1
- 229910052697 platinum Inorganic materials 0.000 description 1
- 239000002904 solvent Substances 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- 239000003115 supporting electrolyte Substances 0.000 description 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 1
Classifications
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M12/00—Hybrid cells; Manufacture thereof
- H01M12/08—Hybrid cells; Manufacture thereof composed of a half-cell of a fuel-cell type and a half-cell of the secondary-cell type
- H01M12/085—Zinc-halogen cells or batteries
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
- Y02E60/10—Energy storage using batteries
Landscapes
- Engineering & Computer Science (AREA)
- Manufacturing & Machinery (AREA)
- Chemical & Material Sciences (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Electrochemistry (AREA)
- General Chemical & Material Sciences (AREA)
- Hybrid Cells (AREA)
Description
Ａ 産業上の利用分野
本発明は亜鉛−臭素二次電池の電流効率向上に
係り、詳しくは正極電解液の状態に関するもので
ある。
Ｂ 発明の概要
本発明は、容易に従来の作業・装置に付加して
電池を構成することができ、電流効率を向上する
ことのできる亜鉛−臭素二次電池を得るため、完
全放電後且つ充電前の状態で、負極電極面上に金
属亜鉛が析出してなく正極電解液中に正極活物質
の臭素（Br2）が残存している構成としたもので
ある。
Ｃ 従来の技術
亜鉛−臭素電池はエネルギー密度が高い観点か
ら近年この実用化が研究されている。例えば第１
図は電解液循環型の亜鉛−臭素二次電池の基本的
構成を示すもので、図中１は単セル、２は正極
室、３は負極室、４は隔膜（セパレータ）、５は
正極、６は負極、７は正極電解液、８は負極電解
液、９は正極液貯槽、１０は負極液貯槽、１１お
よび１２はポンプである。
亜鉛−臭素二次電池は、充電時に正極５におい
て臭素イオンが酸化され、臭素分子となり電解液
中に入る。
2Br-→Br2＋2e-
また負極６においては次式の反応により亜鉛が
電極表面に析出する。
Zn2+＋2e-→＋Zn
従つて全化学反応は
Zn2+＋2Br-→Br2＋Zn
となる。
第１図は充電時を示したものであり、放電時は
上記反応と逆方向の化学反応が起こる。これら亜
鉛−臭素電池においては従来からクーロン効率
（電流効率）の向上が望まれていた。
一般に亜鉛−臭素電池の電圧効率を向上せしめ
るためには、正負極間の距離を短くし電圧損失を
小さくするか、又は使用する電解液中に電導度を
向上せしめる支持電解液を添加すること等の手段
により電圧効率は通常問題とならない程、高効率
を維持しうる。
然しながら、亜鉛−臭素電池のエネルギー効率
は上述の電流効率と電圧効率との積で表わされる
ために、いくら電圧効率が高くても、電流効率が
低いと結局、エネルギー効率は悪くなるので亜鉛
−臭素電池における低い電流効率の向上が従来か
らの課題であつた。
従来、亜鉛−臭素電池の電流効率の向上に関す
る因子としては、隔膜、電極、電解液の流速、隔
膜−電極間の距離、電流密度、充電深度等が考え
られている。
先ず、隔膜の作用は、充電時発生する正極室の
臭素を対極の負極室に拡散させない機能を有する
が、安価な多孔質の隔膜はもちろんイオン交換膜
でも完全に拡散を阻止出来ず、従つて自己拡散を
少なくし、電流効率を向上せさるために隔膜の厚
みを厚くする方法が採用される場合があるが、こ
れは逆に膜抵抗を増加し電圧効果を低下せしめる
欠点を有するもので好ましくない。
また、電極としては、特に正極側での放電々位
の高いもの程電流効率も良くなるので、放電々位
向上の為に電極に特殊な工夫をこらす必要があり
経済上有利ではない。
電解液の流速においても、電流効率の点から最
適流速条件を求めることは困難であり、例え最適
流速が求められたとしても、当然負極側の流速も
同じ流速にする必要があり、この流速が負極室に
おいても最適になるとは言難い。
Ｄ 発明が解決しようとする課題
以上述べた以外の残りの隔膜−電極間の距離、
電流密度、充電深度等の因子は、電流効率の向上
のみで決定される訳ではない、それ以上に亜鉛−
臭素電池全体のエネルギー密度の点からも検討さ
れる内容であり、一般的に電流効率の向上のため
ばかりで簡単に決定されない因子である。この様
に亜鉛−臭素電池の電流効率向上対策としては他
の方法で改善する必要が従来から望まれていた。
本発明者は負極室拡散臭素と析出亜鉛による自
己放電以上に、電流効率の因子として充放電時の
正極側の臭素濃度が大きく影響していることを実
験的に見出し本発明に至つたものである。
本発明は、電流効率が向上した亜鉛−臭素二次
電池を得ることを目的とする。
Ｅ 課題を解決するための手段
本発明に係る亜鉛−臭素二次電池では、電解液
を循環させる亜鉛−臭素二次電池において、
完全放電後且つ充電前の状態で、負極電極面上
に金属亜鉛が析出してなく正極電解液中に正極活
物質の臭素（Br2）が残存しているものである。
Ｆ 作 用
本発明においては、亜鉛−臭素二次電池におい
て、完全放電後且つ充電前の状態で、負極電極面
上に金属亜鉛が析出してなく正極電解液中に正極
活物質の臭素（Br2）が残存しているものであ
る。即ち、従来電解液の組成は活物質である陽イ
オン形成メタルとしての亜鉛の全モル数と、陰イ
オン形成物質としての臭素の全モル数とは、１：
１（Zn：Br2の比以下省略）となつているが、本
発明の亜鉛−臭素二次電池では、亜鉛−臭素電池
組立てを行なつた後又は完全放電後且つ充電前の
正極電解液中に臭素を特定量添加し、亜鉛全モル
数：臭素全モル数＝１：１＋αとした電池であ
る。
一般的に亜鉛−臭素二次電池の電流効率を決め
る要因としては、正極室で発生し隔膜４を通して
負極室に拡散する臭素と負極電着亜鉛との自己放
電、および、正極側での放電時における電極電位
及び電極と電解液中の臭素との反応状態等が大き
な因子である。
一方、負極側においては、充電時生成する電着
亜鉛の溶解、または電極からの剥離等がない限り
電流効率を低下せしめる要因とならないのが一般
的である。
ところで、本発明において負極室拡散臭素と析
出亜鉛による自己放電以上に、電流効率の因子と
して充放電時の正極側の臭素濃度が大きく影響す
る知見を得た。
詳しくは、例えば、亜鉛−臭素電池において或
る一定条件、即ち片方は臭素（Br2純度97％以
上）をあらかじめ正極電解液に添加し、一方は臭
素未添加の状態で運転した場合、隔膜による自己
拡散からみれば電流効率の向上は充電条件が同一
であれば臭素の有無にかかわらず同一である筈で
ある。また逆に臭素（Br2）を添加した方は充電
初期より負極室と正極室の臭素（Br2）濃度勾配
が高いので、負極室への自己拡散も多くなり、そ
の結果負極の電着亜鉛と自己放電を起こし、電流
効率は臭素（Br2）未添加の場合よりも悪くなる
ものと予想されていた。
然しながら、実験の結果は予期に反して逆に臭
素添加の方が電流効率の向上を示すことを見知し
た。このことは、前述の電流効率の向上の因子と
して正極側、特に放電末期における臭素濃度の影
響が大きいことの証明となつた。
すなわち、電解液に臭化亜鉛（ZnBr2）水溶液
のみを使用した場合、充電時に印加されて正極で
生成する活物質である臭素（Br2）の一部は電解
液の溶媒である水と水和して臭化水和物となり、
正極室、正極液貯槽等を循環する。また、一部電
池の構成材料に吸収される。一方、印加されて負
極で生成する活物質である亜鉛は電極面に析出す
る。ところで、放電時の初期では、正極では循環
液中に臭素（Br2）が豊富にあるため、放電の効
率は問題ないが、放電中期以降では、臭素が正極
電極付近で乏しくなるため、放電の効率が下が
る。
本願では正極電解液が、あらかじめ余分に臭素
（Br2）を含んでおり、充電によつて得られる臭
素（Br2）に加えて充分な臭素（Br2）濃度が得
られるため、放電中期以降であつても正極電極付
近で活物質として利用できる臭素が充分に存在す
ることになり、放電効率の低下が防止される。
以上のことより、亜鉛−臭素電池において亜鉛
臭素電池組立後または完全放電後等の充電前に正
極室電解液に臭素を添加し、好ましくは0.2モ
ル／以上添加し、亜鉛全モル数：臭素全モル数
＝１：（１＋0.2）以上とすれば、完全放電後の正
極液で臭素（Br2）を0.2モル／以上含有維持す
ることとなり、充放電サイクルの運転において電
流効率を向上させる効果があり、これ以下におい
てはその効果が少なく0.2〜1.0モル／が好まし
い結果が得られることが、実験により確認され
た。
Ｇ 実施例
実施例 １
第１図に示す如き構造の亜鉛−臭素二次電池の
単電池において、電極面積400cm2の白金電極を使
用し、電解液として臭化亜鉛（ZnBr2）３モル／
溶液、隔膜として厚み0.4mmの微細多孔質を使
用し、充放電々流密度を20ｍＡ／cm2、膜−電極間
距離を１mm、電解液流速を100cm3／分、正極、負
極質液量500cm3、充電時間を８時間、充電深度80
％、カツトオフ電圧０ボルト、動作時の液温25℃
以上の条件で正極側に臭素（純度97％以上）を初
期より未添加、0.2モル／、0.5モル／、１モ
ル／添加した４種類の正極液を用い前述の条件
で電流効率、電圧効率、エネルギー効率を測定し
た。
なお、電流効率（％）（クーロン効率）とは、
充電した電気量（電流I1×充電時間H1）に対し
て、放電した電気量（電流I2×充電時間H2）の
割合であり、次式で導き出される。
電流効率(%)＝（I2×H2）／（I1×H1）×100
また、電圧効率（％）とは、充電時の電圧（平
均電圧V1）に対する放電時の電圧（平均電圧V2）
の割合であり、次式で導き出される。
電圧効率(%)＝V2／V1×100
また、エネルギー効率（％）とは、充電時の電
力量（V1×I1×H1）に対する放電した電力量
（V2×I2×H2）の割合であり、次式で導き出され
る。
エネルギー効率(%)＝（V2×I2×H2）／（V1×I1×H1
）×100
上述のように、充電時の電流I1と充電時間H1
と電圧V1を測定し、放電時の電流I2と充電時間
H2と電圧V2を測定して、夫々を求めた結果を次
の第１表に示す。
A. Industrial Application Field The present invention relates to improving the current efficiency of a zinc-bromine secondary battery, and specifically relates to the state of the positive electrode electrolyte. B. Summary of the Invention The present invention aims to provide a zinc-bromine secondary battery that can be easily added to conventional work/equipment to construct a battery and that can improve current efficiency. In the previous state, metallic zinc is not deposited on the negative electrode surface and bromine (Br 2 ), which is a positive electrode active material, remains in the positive electrode electrolyte. C. Prior Art Zinc-bromine batteries have been studied for practical use in recent years because of their high energy density. For example, the first
The figure shows the basic configuration of an electrolyte circulation type zinc-bromine secondary battery. In the figure, 1 is a single cell, 2 is a positive electrode chamber, 3 is a negative electrode chamber, 4 is a diaphragm (separator), 5 is a positive electrode, 6 is a negative electrode, 7 is a positive electrode electrolyte, 8 is a negative electrode electrolyte, 9 is a positive electrode liquid storage tank, 10 is a negative electrode liquid storage tank, and 11 and 12 are pumps. In the zinc-bromine secondary battery, during charging, bromine ions are oxidized at the positive electrode 5 and become bromine molecules that enter the electrolyte. 2Br - →Br 2 +2e - Also, at the negative electrode 6, zinc is deposited on the electrode surface by the reaction of the following formula. Zn 2+ +2e - →+Zn Therefore, the total chemical reaction is Zn 2+ +2Br - →Br 2 +Zn. FIG. 1 shows the charging state, and during discharging, a chemical reaction occurs in the opposite direction to the above reaction. It has been desired to improve the Coulombic efficiency (current efficiency) of these zinc-bromine batteries. Generally, in order to improve the voltage efficiency of zinc-bromine batteries, it is necessary to shorten the distance between the positive and negative electrodes to reduce voltage loss, or to add a supporting electrolyte to the electrolyte used to improve conductivity. By this means, voltage efficiency can be maintained so high that it usually does not become a problem. However, the energy efficiency of a zinc-bromine battery is expressed as the product of the above-mentioned current efficiency and voltage efficiency, so no matter how high the voltage efficiency is, if the current efficiency is low, the energy efficiency will eventually deteriorate. Improving the low current efficiency of batteries has been a challenge for a long time. Conventionally, factors related to improving the current efficiency of zinc-bromine batteries include the diaphragm, the electrodes, the flow rate of the electrolyte, the distance between the diaphragm and the electrode, the current density, the depth of charge, and the like. First, the diaphragm has the function of preventing bromine generated in the positive electrode chamber during charging from diffusing into the negative electrode chamber of the counter electrode, but not only inexpensive porous diaphragms but also ion exchange membranes cannot completely prevent the diffusion. In order to reduce self-diffusion and improve current efficiency, a method of increasing the thickness of the diaphragm is sometimes adopted, but this method has the disadvantage of increasing membrane resistance and reducing the voltage effect, so it is not preferable. do not have. In addition, as for the electrode, the higher the discharge level, especially on the positive electrode side, the better the current efficiency, so it is necessary to make special arrangements for the electrode in order to improve the discharge level, which is not economically advantageous. Regarding the flow rate of the electrolyte, it is difficult to determine the optimal flow rate conditions from the point of view of current efficiency, and even if the optimal flow rate is determined, the flow rate on the negative electrode side must of course be the same, and this flow rate is It is difficult to say that the negative electrode chamber is also optimal. D Problem to be solved by the invention The remaining distance between the diaphragm and the electrode other than those mentioned above,
Factors such as current density and depth of charge are not determined only by improving current efficiency;
This is a matter that is also considered from the point of view of the energy density of the entire bromine battery, and is generally a factor that is not easily determined because it is only for improving current efficiency. As described above, it has been desired to use other methods to improve the current efficiency of zinc-bromine batteries. The present inventor has experimentally discovered that the bromine concentration on the positive electrode side during charging and discharging has a greater influence on current efficiency than the self-discharge caused by diffused bromine and precipitated zinc in the negative electrode chamber, leading to the present invention. be. An object of the present invention is to obtain a zinc-bromine secondary battery with improved current efficiency. E Means for Solving the Problems In the zinc-bromine secondary battery according to the present invention, in a zinc-bromine secondary battery in which an electrolyte is circulated, metal zinc is deposited on the negative electrode surface after complete discharge and before charging. is not precipitated, and the positive electrode active material bromine (Br 2 ) remains in the positive electrode electrolyte. F Function In the present invention, in a zinc-bromine secondary battery, after complete discharge and before charging, metallic zinc is not deposited on the negative electrode surface and bromine (Br) of the positive electrode active material is present in the positive electrode electrolyte. 2 ) remains. That is, the composition of a conventional electrolytic solution is such that the total number of moles of zinc as a cation-forming metal active material and the total number of moles of bromine as an anion-forming substance are 1:
1 (ratio below Zn:Br 2 is omitted), but in the zinc-bromine secondary battery of the present invention, after assembling the zinc-bromine battery or after fully discharging and before charging, In this battery, a specific amount of bromine is added to make the total number of moles of zinc: total number of moles of bromine = 1:1 + α. In general, the factors that determine the current efficiency of zinc-bromine secondary batteries include self-discharge between bromine and negative electrode electrodeposited zinc that occurs in the positive electrode chamber and diffuses into the negative electrode chamber through the diaphragm 4, and the self-discharge during discharge on the positive electrode side. The major factors are the electrode potential and the state of reaction between the electrode and bromine in the electrolyte. On the other hand, on the negative electrode side, unless electrodeposited zinc generated during charging is dissolved or peeled off from the electrode, it generally does not become a factor that reduces current efficiency. By the way, in the present invention, it has been found that the bromine concentration on the positive electrode side during charging and discharging has a greater effect as a factor on current efficiency than the self-discharge due to the negative electrode room diffused bromine and precipitated zinc. In detail, for example, when a zinc-bromine battery is operated under certain conditions, i.e., one side has bromine ( Br2 purity of 97% or more) added to the positive electrode electrolyte and the other side is operated without bromine, the diaphragm From the viewpoint of self-diffusion, the improvement in current efficiency should be the same regardless of the presence or absence of bromine if the charging conditions are the same. Conversely, when bromine (Br 2 ) is added, the concentration gradient of bromine (Br 2 ) between the negative electrode chamber and the positive electrode chamber is high from the beginning of charging, so self-diffusion into the negative electrode chamber increases, and as a result, the electrodeposited zinc on the negative electrode increases. It was predicted that self-discharge would occur and the current efficiency would be worse than when bromine (Br 2 ) was not added. However, the experimental results showed that, contrary to expectations, the addition of bromine showed an improvement in current efficiency. This proves that the bromine concentration on the positive electrode side, especially at the end of discharge, has a large influence as a factor in improving the current efficiency mentioned above. In other words, when only an aqueous zinc bromide (ZnBr 2 ) solution is used as the electrolyte, some of the active material bromine (Br 2 ) that is applied during charging and generated at the positive electrode is mixed with water, the solvent of the electrolyte. to form hydrated bromide,
Circulates through the positive electrode chamber, positive electrode liquid storage tank, etc. In addition, some of it is absorbed by the constituent materials of the battery. On the other hand, zinc, which is an active material produced at the negative electrode upon application, is deposited on the electrode surface. By the way, at the beginning of discharge, there is an abundance of bromine (Br 2 ) in the circulating fluid at the positive electrode, so there is no problem with the discharge efficiency, but after the middle stage of discharge, bromine becomes scarce near the positive electrode, which reduces the efficiency of discharge. Efficiency decreases. In this application, the positive electrode electrolyte contains extra bromine (Br 2 ) in advance, and a sufficient bromine (Br 2 ) concentration can be obtained in addition to the bromine (Br 2 ) obtained by charging. Even in this case, there is sufficient bromine that can be used as an active material near the positive electrode, and a decrease in discharge efficiency is prevented. From the above, in a zinc-bromine battery, bromine is added to the positive electrode compartment electrolyte before charging after assembly or after complete discharge, preferably at least 0.2 mol/mol, so that the total number of moles of zinc is equal to the total number of bromine. If the number of moles = 1: (1 + 0.2) or more, the cathode solution after complete discharge will maintain a content of 0.2 mole or more of bromine (Br 2 ), which has the effect of improving current efficiency during charge/discharge cycle operation. It has been confirmed through experiments that the effect is small below this value, and preferable results are obtained at 0.2 to 1.0 mol/mole/mole/mole/mole. G Examples Example 1 In a single cell of a zinc-bromine secondary battery having the structure shown in Fig. 1, platinum electrodes with an electrode area of 400 cm 2 were used, and zinc bromide (ZnBr 2 ) was used as the electrolyte at 3 mol/min.
A microporous material with a thickness of 0.4 mm was used as the solution and diaphragm, the charging/discharging current density was 20 mA/cm 2 , the distance between the membrane and the electrode was 1 mm, the electrolyte flow rate was 100 cm 3 /min, and the positive and negative electrode liquid volumes were 500 cm 3 , charging time 8 hours, charging depth 80
%, cut-off voltage 0 volts, liquid temperature during operation 25℃
Under the above conditions, using four types of catholytes in which bromine (purity of 97% or more) was not added, 0.2 mol/, 0.5 mol/, and 1 mol/ bromine was added to the positive electrode side from the beginning, current efficiency, voltage efficiency, Energy efficiency was measured. In addition, current efficiency (%) (coulomb efficiency) is
It is the ratio of the discharged quantity of electricity (current I 2 × charging time H 2 ) to the charged quantity of electricity (current I 1 × charging time H 1 ), and is derived from the following formula. Current efficiency (%) = (I 2 × H 2 ) / (I 1 × H 1 ) × 100 Voltage efficiency (%) is the ratio of the voltage during discharging (average voltage V 1 ) to the voltage during charging (average voltage V 1 ). voltage V2 )
It is the ratio of , and is derived from the following formula. Voltage efficiency (%) = V 2 / V 1 × 100 Energy efficiency ( % ) is the amount of electricity discharged ( V 2 × I 2 × H 2 ), which is derived from the following formula. Energy efficiency (%) = (V 2 × I 2 × H 2 ) / (V 1 × I 1 × H 1
) × 100 As mentioned above, the charging current I 1 and the charging time H 1
and measure the voltage V 1 , the current I 2 during discharging and the charging time
H 2 and voltage V 2 were measured and the results are shown in Table 1 below.
【表】
第１表に示すように、電圧効率は臭素添加量の
有無にかかわらず87.5％で変らないものの、電流
効率は臭素添加した場合約20％の向上を示した。
実施例 ２
隔膜として厚み1.2mmの微細多孔膜を使用した
以外実施例１と同様の条件で臭素添加試験を行な
いその比較を次の第２表に示す。[Table] As shown in Table 1, although the voltage efficiency remained unchanged at 87.5% regardless of the amount of bromine added, the current efficiency improved by about 20% when bromine was added. Example 2 A bromine addition test was conducted under the same conditions as in Example 1 except that a microporous membrane with a thickness of 1.2 mm was used as the diaphragm, and the comparison is shown in Table 2 below.
【表】
第２表に示すように、隔膜の厚さが厚くなつた
ため電圧効率は実施例１より低下したが電流効率
は実施例１と同様に臭素添加の場合20％程度臭素
未添加より向上を示した。
実施例 ３
隔膜として、陽イオン交換膜（デユポン社製
Nation 117）を使用し他は全て実施例１と同様
に行なつた結果を第３表に示す。[Table] As shown in Table 2, the voltage efficiency was lower than in Example 1 due to the increased thickness of the diaphragm, but the current efficiency was improved by about 20% in the case of bromine addition, as in Example 1, than in the case of no bromine addition. showed that. Example 3 A cation exchange membrane (manufactured by DuPont) was used as a diaphragm.
Table 3 shows the results of the same procedure as in Example 1 except that Nation 117) was used.
【表】
第３表に示すように、電流効率において臭素添
加により約13％の向上を示した。
以上の実施例の結果より亜鉛−臭素電池の電流
効率は亜鉛全モル数：臭素全モル数＝１：（１＋
0.2）以上となるよう臭素を0.2モル／以上添加
した正極液を使用すると向上することが確認され
た。
以上のように本発明は、亜鉛全モル数（Zn）：
臭素全モル数（Br2）＝１：１＋αとなるよう電
池組立後または完全放電後に臭素を添加した正極
液を有する亜鉛−臭素電池であり、容易に従来の
装置に付加して電池を構成することができ、電流
効率を向上することができる。その結果エネルギ
ー効率を向上でき、添加臭素のコストを上回るメ
リツトを有する等の効果を有する。
Ｈ 発明の効果
以上説明したとおり、本発明の亜鉛−臭素二次
電池は、完全放電後且つ充電前の状態で、負極電
極面上に金属亜鉛が析出してなく正極電解液中に
正極活物質の臭素（Br2）が残存しているもので
ある。即ち、亜鉛全モル数（Zn）：臭素全モル数
（Br2）＝１：１＋αとなるように、電池組立後ま
たは完全放電後且つ充電前の正極電解液に臭素を
添加したものであり、容易に従来の作業・装置に
付加して電池を構成することにより、電流効率を
向上することができる。その結果、エネルギー効
率を向上でき、添加臭素のコストを上回るメリツ
トを有する等の有用な電池が得られるという効果
がある。[Table] As shown in Table 3, the addition of bromine showed an improvement of about 13% in current efficiency. From the results of the above examples, the current efficiency of the zinc-bromine battery is: total number of moles of zinc: total number of moles of bromine = 1: (1+
It was confirmed that an improvement can be achieved by using a catholyte containing 0.2 mol/or more of bromine to achieve a value of 0.2) or more. As described above, the present invention provides the total number of moles of zinc (Zn):
This is a zinc-bromine battery that has a positive electrode liquid in which bromine is added after battery assembly or complete discharge so that the total number of moles of bromine (Br 2 ) = 1:1 + α, and it can be easily added to conventional equipment to configure a battery. It is possible to improve current efficiency. As a result, energy efficiency can be improved, and the cost of added bromine has advantages that exceed the cost. H. Effects of the Invention As explained above, the zinc-bromine secondary battery of the present invention has no metallic zinc deposited on the negative electrode surface and no positive active material in the positive electrolyte after complete discharge and before charging. of bromine (Br 2 ) remains. That is, bromine is added to the positive electrode electrolyte after battery assembly or after complete discharge and before charging so that the total number of moles of zinc (Zn): total number of moles of bromine (Br 2 ) = 1:1 + α, Current efficiency can be improved by easily adding it to conventional work/equipment to configure a battery. As a result, a useful battery can be obtained that can improve energy efficiency and has advantages that exceed the cost of added bromine.
第１図は電解液循環型の亜鉛−臭素二次電池の
基本的構成を示す模式図である。
１：単セル、２：正極室、３：負極室、４：隔
膜、５：正極、６：負極、７：正極液、８：負極
液、９：正極液貯槽、１０：負極液貯槽、１１，
１２：ポンプ。
FIG. 1 is a schematic diagram showing the basic structure of an electrolyte circulation type zinc-bromine secondary battery. 1: Single cell, 2: Positive electrode chamber, 3: Negative electrode chamber, 4: Diaphragm, 5: Positive electrode, 6: Negative electrode, 7: Positive electrode liquid, 8: Negative electrode liquid, 9: Positive electrode liquid storage tank, 10: Negative electrode liquid storage tank, 11 ，
12: Pump.
Claims (1)
いて、 完全放電後且つ充電前の状態で、負極電極面上
に金属亜鉛が析出してなく正極電解液中に正極活
物質の臭素（Br2）が残存していることを特徴と
する亜鉛−臭素二次電池。 ２ 前記完全放電後且つ充電前の状態で、正極電
解液に残存している臭素（Br2）の濃度が、0.2モ
ル／以上であることを特徴とする特許請求の範
囲第１項記載の亜鉛−臭素二次電池。[Claims] 1. In a zinc-bromine secondary battery in which an electrolyte is circulated, after complete discharge and before charging, metallic zinc is not deposited on the negative electrode surface and the positive electrode active material is present in the positive electrode electrolyte. A zinc-bromine secondary battery characterized in that bromine (Br 2 ) remains. 2. The zinc according to claim 1, wherein the concentration of bromine (Br 2 ) remaining in the positive electrode electrolyte after the complete discharge and before charging is 0.2 mol/or more. - Bromine secondary battery.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP57196803A JPS5987781A (en) | 1982-11-11 | 1982-11-11 | Zinc bromine battery |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP57196803A JPS5987781A (en) | 1982-11-11 | 1982-11-11 | Zinc bromine battery |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPS5987781A JPS5987781A (en) | 1984-05-21 |
| JPH021355B2 true JPH021355B2 (en) | 1990-01-11 |
Family
ID=16363903
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP57196803A Granted JPS5987781A (en) | 1982-11-11 | 1982-11-11 | Zinc bromine battery |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPS5987781A (en) |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| KR101815281B1 (en) * | 2015-09-23 | 2018-01-04 | 롯데케미칼 주식회사 | Method for controling operation of chemical flow battery |
-
1982
- 1982-11-11 JP JP57196803A patent/JPS5987781A/en active Granted
Also Published As
| Publication number | Publication date |
|---|---|
| JPS5987781A (en) | 1984-05-21 |
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